Purification, crystallization and preliminary crystallographic studies of SPCI-chymotrypsin complex at 2.8 A resolution.
A binary complex of the Schizolobium parahyba chymotrypsin inhibitor (SPCI) with chymotrypsin was purified by size-exclusion chromatography and crystallized by the sitting-drop vapour-diffusion method with 100 mM MES-NaOH pH 5.5, 20%(w/v) PEG 6000, 200 mM LiCl as precipitant and 200 mM nondetergent sulfobetaine molecular weight 201 Da (NDSB-201) as an additive. SPCI is a small protein with 180 amino-acid residues isolated from S. parahyba seeds and is able to inhibit chymotrypsin at a 1:1 molar ratio by forming a stable complex. X-ray data were collected to 2.8 A resolution from a single crystal of the SPCI-chymotrypsin binary complex under cryogenic conditions. The crystal belongs to space group P2(1)2(1)2(1), with unit-cell parameters a = 45.28, b = 64.57, c = 169.23 A, and the R(merge) is 0.122 for 11 254 unique reflections. A molecular-replacement solution was found using the preliminary crystal structure of SPCI and the structure of chymotrypsin (PDB code 4cha) independently as search models.
da Silva
Adelson Joel
AJ
Biophysics Laboratory, Biological Sciences Institute, University of Brasília, Brasília-DF, 70910-900, Brazil.
Teles
Rozeni Chagas Lima
RC
Esteves
Gisele Ferreira
GF
dos Santos
Camila Ramos
CR
Barbosa
João Alexandre Ribeiro Gonçalves
JA
de Freitas
Sonia Maria
SM
D002852:Chromatography, Ion Exchange; D002918:Chymotrypsin / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry*
C096591:Chymotrypsin inhibitor protein, Schizolobium parahybum; D010940:Plant Proteins; D002918:Chymotrypsin